In　the　paper,　we　present　a　novel　tortoise-like　flexible　micro-robot　with　four　legs　which　can　crawl　and　swim　underwater.　These　legs　are　actuated　by　ICPF　(Ionic　Conducting　Polymer　Film)　which　is　a　kind　of　smart　film　and　has　the　characteristics　of　flexibility,　good　response　and　being　driven　by　a　low　voltage.　For　improving　the　robot＇s　reliability　and　feasibility,　we　establish　the　micro-robot＇s　dynamic　model　by　applying　Pseudo-Rigid-Body-Dynamic-Model　(PRBDM).　The　model　is　established　by　considering　the　dynamic　effect　of　the　robot,　which　is　based　on　statics　and　kinematics.　Then,　the　frequency　analysis　of　a　micro-robot　based　on　PRBDM　is　investigated.　Based　on　the　PRBDM,　the　relation　between　the　robot＇s　structure　parameters　and　its　natural　frequency　is　theoretically　derived　and　a　numerical　computation　of　the　robot　is　performed.